1. Field of the Invention
The invention relates to a trivalent rare earth metal ion exchanged ferrierite. More particularly the invention relates to ferrierite containing one or more trivalent rare earth metals occupying at least 10% of its cation exchange capacity and to its preparation by hydrothermal ion exchange.
2. Background of the Invention
Ion exchangeable, natural and synthetic crystalline aluminosilicates of the zeolite type are well known and are useful as catalysts and molecular sieves. One such use comprises catalytically dewaxing waxy paraffinic feeds to reduce their pour point and convert the waxy material to useful products such as fuel and lubricating oil fractions, as is known. Such feeds have included petroleum derived wax containing oils, heavy oil fractions and slack wax. Dewaxing catalysts comprise a catalytic metal component, a natural or synthetic, crystalline aluminosilicate or zeolite molecular sieve component and often one or more additional refractory metal oxide components. Molecular sieves which have been found useful for dewaxing petroleum oil fractions and slack wax include, for example, ferrierite (U.S. Pat. Nos. 4,343,692 and 4,795,623), mordenite (U.S. Pat. No. 3,902,988), ZSM-23 and ZSM-35 (U.S. Pat. No. 4,222,855), ZSM-5 and ZSM-11 (U.S. Pat. No. 4,347,121) and ZSM-5 (U.S. Pat. No. 4,975,177). Both the '692 and '623 patents stress that it is the acid or H+ form of ferrierite which is active for dewaxing. The '623 patent discloses that ferrierite, when associated with particular catalytic metals, can also be useful as a catalyst for hydrocracking, isomerization, dealkylation and cracking. U.S. Pat. Nos. 4,584,286 and 5,288,475 relating to ZSM-35, a ferrierite-type of material, suggest it may be ion exchanged with hydrogen, a hydrogen precursor or a wide variety of metals, including rare earths, by the well known ion exchange technique of contacting the sieve with an aqueous salt solution of the metal at a temperature no greater than the boiling point of the solution, followed by washing.